This invention relates to the ventilation of enclosures that are at least in part formed by a flexible wall. More particularly, the invention relates to the provision of a vent forming attachment for a flexible wall comprising two members that are brought together from opposite sides of the flexible wall and are screwed together where they meet at an opening in the flexible wall, for securing them together and to the flexible wall.
Vent forming attachments for flexible wall enclosures are disclosed by the following U.S. Pat. No. 2,939,375, granted Jun. 7, 1960 to J. Herman; U.S. Pat. No. 3,024,717, granted Mar. 13, 1962 to Edward G. Rozek; U.S. Pat. No. 3,892,169, granted Jul. 1, 1975 to Frank R. Jarnot; U.S. Pat. No. 4,184,414, granted Jan. 22, 1980 to Frank R. Jarnot; U.S. Pat. No. 4,379,468, granted Apr. 12, 1983 to Steve Szukhent; and U.S. Pat. No. 4,625,468, granted Dec. 2, 1986 to Viktor E. Hampel.
The vent forming attachments disclosed by these patents are relatively complex in construction and are difficult to install and may lack a firm attachment to the wall structure when installed. There is a need for a vent forming attachment that is simple in construction, has a very few parts, is easy to attach, and, when attached, makes a secure connection with the wall structure. An object of the present invention is to provide a vent forming attachment that fulfills this need.
The present invention provides a vent forming attachment for a flexible wall. The attachment is attachable to the wall at an opening in the wall. According to an aspect of the invention, the attachment comprises a first ring member and a second ring member. The first ring member has an axial center opening that is radially outwardly bounded by an axial nipple that is sized to fit into the opening in the wall. The nipple includes a base and external threads that extend axially from the base. The first ring member also includes a first inner side surface that extends radially outwardly from the base of the nipple. The second ring member has an axial center opening that includes internal threads that match and mate with the external threads on the nipple. The second ring member also has a second inner side surface that extends radially outwardly from the center opening in the second ring member. The first ring member is positionable with its nipple in the opening in the wall and its inner side surface against a first side of the wall. The second ring member is positionable with its inner side surface directed toward a second side of the wall opposite said first side of the wall, and is rotatable to cause its internal threads to threadedly engage the external threads on the nipple of the first ring member. This positioning and rotation causes the first and second ring members to become connected together and a portion of the wall that immediately surrounds the opening in the wall to be trapped by and between the two inner side surfaces of the two ring members. One of the ring members has projecting portions on the inner side surface thereof configured to be urged against said portion of the wall when the first and second ring members are connected together to trap said portion of the wall. This inhibits rotation of the attachment relative to the wall. In addition, one of the ring members has a plurality of fins extending across its axial center opening to form a louvered opening. A plurality of ribs perpendicular to the fins extend between and interconnect each pair of adjacent fins to strengthen the fins.
Both the projecting portions and the fins may be provided on only one of the ring members or on both of the ring members. A ring member including fins may also include projecting portions. Alternatively, the projecting portions may be provided on a different ring member that does not include fins.
The projecting portions on the inner side surface may have various configurations. Preferably, the projecting portions comprise a plurality of pointed raised dimples. In the preferred embodiment, these dimples are circumferentially spaced around the circumference of the inner side surface. The projecting portions may also take various other configurations. For example, the portions may form an annular ridge or a spiral ridge extending around the inner side surface. Either type of ridge might be continuous or formed of a plurality of spaced sections.
Flow passageways for air to allow the desired venting action are provided between adjacent fins. If it is desired to divide these flow passageways into smaller passageways sufficiently small to inhibit passage of insects through the attachment, the attachment may also be provided with a screen. Such a screen would preferably be carried by the first ring member and cover the center opening of the first ring member.
To improve the appearance of the attachment and minimize any obstruction of flow through the attachment without sacrificing strength, the ribs that interconnect the fins have a preferred configuration. In this configuration, each fin is downwardly angled, as in most known louvered structures. Each rib connects a mid portion of a lower surface of a first fin and a mid inner portion of an adjacent upper surface of a second fin. This leaves an outer portion of the upper surface free from connection to the rib. The resulting configuration tends to direct flow around the ribs and on through the center openings of the attachment along the upper surface of the second fin adjacent to the rib. As used in reference to the fins, the term xe2x80x9cmidxe2x80x9d refers to a middle position in a chordwise direction of the attachment, and the terms xe2x80x9cinnerxe2x80x9d and xe2x80x9couterxe2x80x9d refer to a position in the axial direction of the attachment with xe2x80x9cinnerxe2x80x9d being relatively close to the axial center of the attachment.
As used herein, the terms xe2x80x9cdownwardlyxe2x80x9d, xe2x80x9clowerxe2x80x9d, xe2x80x9cupperxe2x80x9d, and the like refer to the use orientation illustrated in FIGS. 2-8.
These and other advantages and features of the invention will become apparent from the detailed description of the invention set forth below.